It is useful for various medical diagnostic purposes to utilize a reflectance spectroscope to analyze samples of body fluid, for example, to determine the color of a person's urine. A conventional spectroscope may determine the color of a urine sample disposed on a white, non-reactive pad by illuminating the pad and taking a number of reflectance readings from the pad, each having a magnitude relating to a different wavelength of visible light. The color of the urine on the pad may then be determined based upon the relative magnitudes of red, green, blue and infrared reflectance signals.
Conventional spectroscopes may be used to perform a number of different urinalysis tests utilizing a reagent strip on which a number of different reagent pads are disposed. Each reagent pad may be provided with a different reagent which causes a color change in response to the presence of a certain type of constituent in urine, such as leukocytes (white blood cells) or red blood cells. Such a reagent strip may have ten or more different types of reagent pads.
In a conventional spectroscope, the process of inspecting a reagent strip may be performed by dipping the reagent strip in a urine sample, blotting excess urine from the reagent strip, placing the reagent strip at a designated location in the spectrophotometer, and pressing a start button which causes the spectroscope to begin automatic processing and inspection of the reagent strip.
For example, U.S. Pat. No. 5,654,803, which is assigned to the assignee of the present disclosure, discloses an apparatus and method for determination of non-hemolyzed levels of occult blood in urine. The apparatus is provided with a light bulb for successively illuminating a plurality of different portions of a reagent pad on which a urine sample is disposed, and a detector array for detecting light received from the reagent pad and generating a plurality of reflectance signals in response to light received from a corresponding one of the different portions of the reagent pad. The apparatus is also provided with means for determining whether the magnitude of one of the reflectance signals is substantially different from the magnitude of another of the reflectance signals. Where the body-fluid sample is urine, this capability allows the apparatus to detect the presence of non-hemolyzed levels of occult blood in the urine sample. The light bulb may successively illuminate a plurality of overlapping portions of the reagent pad, and may successively illuminate at least tree different portions of the reagent pad which are linearly offset from each other.
U.S. Pat. No. 5,945,341, which is also assigned to the assignee of the present disclosure, discloses a system for the optical identification of coding on a diagnostic test strip and an automated method for reading a test strip for the analysis of the presence of one or more analytes in a liquid test sample. The method involves the spectrophotometric reading of a test strip which bears at least two marker fields on its surface which are capable of reflecting light at different spectral regions from each other. The means of the spectrophotometer is programmed to discern information concerning the strip, such as what analyte the strip is designed to detect, from the sequences of spectral classifications by spectral reflectance measurements of the strip's marker fields.
U.S. Pat. No. 6,239,445, which is assigned to the assignee of the present disclosure, discloses an optical inspection apparatus for inspecting a liquid sample, such as urine. The apparatus includes a tray that is adapted to be physically coupled to a first liquid sample carrier and a second liquid sample carrier, which are both adapted to hold a liquid sample. The first liquid sample carrier is of a first type, such as a reagent cassette, and the second liquid sample carrier is of a second type, such as a reagent strip, different from the first type. The apparatus has a light source adapted to illuminate one of the liquid samples associated with one of the liquid sample carriers when the liquid sample carrier is coupled to the tray at an inspection location and a detector adapted to receive light from the liquid sample when the liquid sample is being illuminated by the light source.
What is still desired is a new and improved tray assembly including a support tray that is adapted to be physically coupled to at least two different liquid sample carriers such as a reagent cassette and a reagent strip. Preferably, the new and improved tray assembly will be user-friendly and easy to use. In addition, the new and improved tray assembly will preferably be easy to clean and less likely to contaminate the optical inspection apparatus with excess bodily fluids from the liquid sample carriers.